This is one of my favorite apps. Its called "Torque" and its for the Android platform.
You have to have a bluetooth OBDII scanner (About 20-30$ on eBay) and this app will tell you EVERYTHING about your vehicle. Speed, RPMs, MPGs, Avd MPGs, Coolant Temp, Intake air temp, and probably 30 more.
It also reads Check Engine codes, and you can reset the codes (Turn your check engine light off) with your phone.
Mine is nothing serious, just an EGR code, I need to clean mine out.
And sorry if the quality is bad, it was on my iPod Touch 4g with "HD Video Recording" lol
